Vane pump

ABSTRACT

A vane pump includes an annular concave portion formed in an outer circumferential surface of the rotor, both side surfaces are inclined so as to approach each other towards a bottom surface.

TECHNICAL FIELD

The present invention relates to a vane pump.

BACKGROUND ART

JP2006-125210A discloses a vane pump having a cut-out portion formed in a side surface of a cam ring that is in contact with a side plate. The cut-out portion is formed in a portion facing a suction concave portion formed in the side plate. In the vane pump disclosed in JP2006-125210A, a suction port is formed by the suction concave portion and the cut-out portion.

SUMMARY OF INVENTION

In the vane pump disclosed in JP2006-125210A, as a rotor is rotated, working oil is sucked into pump chambers defined between vanes through the suction port from a passage formed between an outer circumference of the cam ring and an inner circumference of a body bore. However, with the vane pump disclosed in JP2006-125210A, because a flow path through which the working oil flows into the pump chambers from the suction port is curved, a pressure loss tends to be caused when the working oil is sucked. Therefore, there is a risk in that the working oil may not be sucked at a sufficient amount when the vane pump is rotated at a high speed, for example.

It is an object of the present invention to improve a suction efficiency of working fluid in a vane pump.

According to an aspect of the present invention, a vane pump includes: a rotor configured to be driven rotationally; a plurality of vanes provided on the rotor so as to be able to reciprocate in a radial direction of the rotor; a cam ring having an inner circumference cam face with which tip-end portions of the plurality of vanes are brought into sliding contact as the rotor rotates; a first side member and a second side member arranged so as to sandwich the rotor and the cam ring; a pump chamber partitioned by the rotor, the cam ring, the adjacent vanes, the first side member, and the second side member; a suction port configured to guide working fluid to the pump chamber; and an annular concave portion formed in an outer circumferential surface of the rotor, wherein both side surfaces of the concave portion are inclined so as to approach each other towards a bottom surface.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional view of a vane pump according to an embodiment of the present invention.

FIG. 2 is a front view of a rotor, vanes, and a cam ring according to the embodiment of the present invention and shows a state in which the rotor, the vanes, and the cam ring are assembled.

FIG. 3 is a perspective view of the rotor according to the embodiment of the present invention.

FIG. 4 is a side view of the rotor according to the embodiment of the present invention.

FIG. 5 is an enlarged view of a cross-section of the vicinities of pump chambers according to the embodiment of the present invention.

FIG. 6 is a front view of a first side plate according to the embodiment of the present invention.

FIG. 7 is a side view of the cam ring, the first side plate, and a second side plate according to the embodiment of the present invention and shows a state in which the first side plate and the second side plate are assembled to the cam ring.

FIG. 8 is a rear view of the cam ring according to the embodiment of the present invention.

FIG. 9 is a front view of the second side plate according to the embodiment of the present invention.

FIG. 10 is a view showing a modification of the embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

A vane pump 100 according to an embodiment of the present invention will be described below with reference to the drawings. The vane pump 100 is used as a hydraulic source for a hydraulic apparatus 1 mounted on a vehicle (for example, a power steering apparatus, a transmission, and so forth). Although description is given to the vane pump 100 using working oil as working fluid in this description, other fluid such as working water etc. may also be used as the working fluid.

As shown in FIG. 1, the vane pump 100 includes a driving shaft 10, a rotor 20 that is linked to the driving shaft 10, a plurality of vanes 30 that are provided in the rotor 20, and a cam ring 40 that accommodates the rotor 20 and the vanes 30.

The driving shaft 10 is rotatably supported by a pump body 50 and a pump cover 60. As a motive force from an engine or an electric motor (not shown) is transmitted to the driving shaft 10, the rotor 20 is rotated by the rotationally driven driving shaft 10.

In the following, the direction along the rotation center axis of the rotor 20 will also be referred to as “the axial direction”, and the radial direction of the rotor 20 and the rotation direction of the rotor 20 during a normal operation of the vane pump 100 will also be referred to simply as “the radial direction” and “the rotation direction”, respectively.

In addition, the vane pump 100 further includes first and second side plates 70 and 80 serving as first and second side members that are arranged so as to sandwich the rotor 20 and the cam ring 40 in the axial direction. The first and second side plates 70 and 80 have side surfaces 70 a and 80 a, respectively, that are brought into contact with the rotor 20 and the cam ring 40. Pump chambers 41 are partitioned by the rotor 20, the cam ring 40, the adjacent vanes 30, the first side plate 70, and the second side plate 80.

Next, a shape of the rotor 20 will be described. FIG. 2 is a front view of the rotor 20, the vanes 30, and the cam ring 40 viewed from the pump cover 60 side after assembly. FIG. 3 is a perspective view of the rotor 20. FIG. 4 is a side view of the rotor 20. FIG. 5 is an enlarged view of a cross-section of the vicinities of the pump chambers 41.

As shown in FIGS. 2 to 4, in the rotor 20, a plurality of slits 22 having opening portions 21 on an outer circumferential surface 20 a are formed in a radiating pattern with predetermined gaps therebetween.

As shown in FIGS. 3 to 5, the rotor 20 includes two annular concave portions 23 and 24 that are formed in the outer circumferential surface 20 a, and an annular ridge portion 25 that is formed between the concave portions 23 and 24 and that projects in the radial direction from the outer circumferential surface 20 a of the rotor 20.

The concave portion 23 includes a side surface 23A that is formed on the side of an end surface 20 b of the rotor 20 facing the first side plate 70, a side surface 23B that is formed on the side of the ridge portion 25, and a bottom surface 23C that is formed of a concave curved surface between the side surface 23A and the side surface 23B. The concave portion 23 is formed to be inclined such that the side surface 23A and the side surface 23B approach each other towards the bottom surface 23C. The bottom surface 23C is formed of the concave curved surface that is continuous with the side surface 23A and the side surface 23B.

The concave portion 24 includes a side surface 24A that is formed on the side of an end surface 20 c of the rotor 20 facing the second side plate 80, a side surface 24B that is formed on the side of the ridge portion 25, and a bottom surface 24C that is formed of the concave curved surface between the side surface 24A and the side surface 24B. The concave portion 24 is formed to be inclined such that the side surface 24A and the side surface 24B approach to each other towards the bottom surface 24C. The bottom surface 24C is formed of the concave curved surface that is continuous with the side surface 24A and the side surface 24B.

As shown in FIG. 5, the side surface 23A of the concave portion 23 and the side surface 24A of the concave portion 24 are provided at positions facing cut-out portions 43 and 44 formed in the cam ring 40, which will be described later.

Referring again to FIG. 2, the vanes 30 are respectively inserted into the slits 22 in a freely slidable manner. Tip-end portions 31 of the vanes 30 face an inner circumferential surface 40 a of the cam ring 40. Base-end portions 32 of the vanes 30 are located in the slits 22, and back pressure chambers 26 are formed on the base-end portions 32 side of the vanes 30 by the slits 22 and the vanes 30.

As the rotor 20 is rotated, the centrifugal force acts on the vanes 30. The vanes 30 are pushed out by the centrifugal force in the direction in which the vanes 30 are projected out from the slits 22, and thus, the tip-end portions 31 of the vanes 30 are pushed against the inner circumferential surface 40 a of the cam ring 40.

The inner circumferential surface 40 a of the cam ring 40 is formed to have a substantially oval shape. In the following, the inner circumferential surface 40 a may also be referred to as “the inner circumference cam face 40 a”.

Because the inner circumference cam face 40 a of the cam ring 40 is formed to have a substantially oval shape, as the rotor 20 is rotated, the vanes 30 reciprocate in the radial direction with respect to the rotor 20. Along with the reciprocating movement of the vanes 30, the pump chambers 41 are repeatedly expanded and contracted.

In this embodiment, as the rotor 20 completes a full rotation, the rotor 20, the vanes 30 reciprocate twice, and the pump chambers 41 repeat the expansion and contraction twice. In other words, the vane pump 100 has, in an alternate manner in the rotating direction, two expansion regions 42 a and 42 c where the pump chambers 41 are expanded and two contraction regions 42 b and 42 d where the pump chambers 41 are contracted.

Referring again to FIG. 1, the pump body 50 is formed with an accommodating hollow portion 51 for accommodating the rotor 20, the cam ring 40, and the first side plate 70. The first side plate 70 is arranged on a bottom surface 51 a of the accommodating hollow portion 51.

An annular groove 52 is formed in the bottom surface 51 a of the accommodating hollow portion 51. A high-pressure chamber 53 into which the working oil that has been discharged from the pump chambers 41 flows is formed by the annular groove 52 and the first side plate 70. The working oil that has been discharged from the pump chambers 41 is supplied to the hydraulic apparatus 1 through the high-pressure chamber 53.

FIG. 6 is a front view of the first side plate 70 viewed from the cam ring 40 side. As shown in FIGS. 1 and 6, the first side plate 70 has, at its center, a through hole 71 penetrating through the first side plate 70. The driving shaft 10 is inserted into the through hole 71.

The first side plate 70 is provided with two discharge ports 72 that guide the working oil discharged from the pump chambers 41 to the high-pressure chamber 53. The discharge ports 72 are provided so as to be respectively located in the contraction regions 42 b and 42 d.

While the pump chambers 41 (see FIG. 2) pass through the contraction regions 42 b and 42 d, the pump chambers 41 are contracted. As the pump chambers 41 are contracted, the pressure of the working oil in the pump chambers 41 is increased, and the working oil in the pump chambers 41 is discharged from the discharge ports 72. In other words, the working oil in the pump chambers 41 is discharged from the discharge ports 72 while the pump chambers 41 pass through the contraction regions 42 b and 42 d. As described above, in the contraction regions 42 b and 42 d, because the working oil is discharged, the contraction regions 42 b and 42 d may also be referred to as “discharge regions”.

The vanes 30 are pushed into the slits 22 to the utmost extent when moving from the contraction region 42 d to the expansion region 42 a and when moving from the contraction region 42 b to the expansion region 42 c, and at these times, the volumes of the pump chambers 41 are minimized. The working oil, the amount of which corresponds to the minimum volume of the pump chambers 41, is not discharged from the pump chambers 41 while the pump chambers 41 pass through the contraction regions 42 d and 42 b and stays in the pump chambers 41. As described above, the minimum volume of the pump chambers 41 does not contribute to the function of the pump and may also be referred to as a dead volume.

The first side plate 70 is formed with two back-pressure passages 73 (see FIGS. 1 and 6) that guide the working oil from the high-pressure chamber 53 to the back pressure chambers 26 (see FIGS. 1 and 2). As shown in FIG. 6, the back-pressure passages 73 have arc shapes centered at the through hole 71 and are formed so as to be located in the expansion regions 42 a and 42 c. Therefore, because the working oil is guided from the high-pressure chamber 53 to the back pressure chambers 26 passing through the expansion regions 42 a and 42 c, the vanes 30 passing through the expansion regions 42 a and 42 c are projected out from the slits 22 (see FIG. 2) due to the pressure in the back pressure chambers 26 and are caused to be pushed against the inner circumferential surface 40 a of the cam ring 40.

As described above, in this embodiment, the vanes 30 are pushed in the direction in which the vanes 30 are projected out from the slits 22 not only by the centrifugal force that is caused by the rotation of the rotor 20 but also by the pressure in the back pressure chambers 26.

Referring again to FIG. 1, the inner diameter of the accommodating hollow portion 51 of the pump body 50 is larger than the outer diameter of the cam ring 40. A fluid chamber 54 is formed between the cam ring 40 and the pump body 50 so as to extend from an outer circumference of the second side plate 80 to an outer circumference of the first side plate 70.

An opening portion of the accommodating hollow portion 51 is closed by the pump cover 60. The pump cover 60 are fixed to the pump body 50 by bolts (not shown). The second side plate 80 is arranged between the pump cover 60 and the cam ring 40.

The pump cover 60 is formed with a low pressure chamber 61. The low pressure chamber 61 is connected to a tank 2 through a low-pressure passage. When the vane pump 100 is operated, the working oil in the tank 2 is supplied to the low pressure chamber 61 through the low-pressure passage. The low pressure chamber 61 communicates with the fluid chamber 54, and the working oil in the tank 2 is supplied to the fluid chamber 54 through the low pressure chamber 61.

The cam ring 40 and the second side plate 80 are provided with side ports 81 serving as suction ports that guide the working oil in the low pressure chamber 61 to the pump chambers 41. In addition, the cam ring 40 and the first side plate 70 are provided with side ports 74 serving as the suction ports that guide the working oil in the fluid chamber 54 to the pump chambers 41. The side ports 74 and 81 are provided so as to be respectively located in the expansion regions 42 a and 42 c.

While the pump chambers 41 pass through the expansion regions 42 a and 42 c (see FIG. 2), the pump chambers 41 are expanded. As the pump chambers 41 are expanded, the pressure in the pump chambers 41 is lowered, and the working oil is sucked into the pump chambers 41 from the side ports 74 and 81. In other words, while the pump chambers 41 pass through the expansion regions 42 a and 42 c, the working oil is sucked into the pump chambers 41 from the side ports 74 and 81. As described above, in the expansion regions 42 a and 42 c, because the working oil is sucked into the pump chambers 41, the expansion regions 42 a and 42 c may also be referred to as “suction region”.

FIG. 7 is a side view showing, from the outer side in the radial direction, a state in which the first side plate 70 and the second side plate 80 are assembled to the cam ring 40. As shown in FIGS. 6 and 7, the side surface 70 a of the first side plate 70 is formed with two recessed portions 75. The recessed portions 75 open at an outer circumferential surface 70 b of the first side plate 70.

FIG. 8 is a rear view of the cam ring 40 viewed from the first side plate 70 side. As shown in FIGS. 7 and 8, an end surface 40 b of the cam ring 40 that is in contact with the first side plate 70 is provided with two cut-out portions 43 that allow communication between an inner circumferential surface and an outer circumferential surface of the cam ring 40. The cut-out portions 43 are located in the expansion regions 42 a and 42 c and are formed so as to extend from the outer circumferential surface 40 d to the inner circumference cam face 40 a of the cam ring 40.

As shown in FIG. 7, in a state in which the first side plate 70 is assembled to the cam ring 40, the recessed portions 75 of the first side plate 70 respectively face the cut-out portions 43 of the cam ring 40. The working oil in the fluid chamber 54 (see FIG. 1) is guided to the pump chambers 41 through ports formed by the recessed portions 75 and the cut-out portions 43. In other words, in this embodiment, the recessed portions 75 of the first side plate 70 and the cut-out portions 43 of the cam ring 40 correspond to the side ports 74.

FIG. 9 is a front view of the second side plate 80 viewed from the pump cover 60 side. As shown in FIGS. 7 and 9, an outer circumferential surface 80 b of the second side plate 80 is provided with two recessed portions 82. The recessed portions 82 are formed so as to extend from the side surface 80 a of the second side plate 80 to a side surface 80 c of the second side plate 80 on the other side of the side surface 80 a.

As shown in FIGS. 2 and 7, an end surface 40 c of the cam ring 40 that is in contact with the second side plate 80 is provided with two cut-out portions 44 that allow communication between an inner circumferential surface and an outer circumferential surface of the cam ring 40. The cut-out portions 44 are located in the expansion regions 42 a and 42 c so as to extend from the outer circumferential surface 40 d to the inner circumference cam face 40 a of the cam ring 40.

As shown in FIG. 7, in a state in which the second side plate 80 is assembled to the cam ring 40, the recessed portions 82 of the second side plate 80 respectively face the cut-out portions 44 of the cam ring 40. The working oil in the low pressure chamber 61 (see FIG. 1) is guided to the pump chambers 41 through ports formed by the recessed portions 82 and the cut-out portions 44. As described above, in this embodiment, the recessed portions 82 of the second side plate 80 and the cut-out portions 44 of the cam ring 40 correspond to the side ports 81.

Next, the operation of the vane pump 100 will be described.

As the motive force from the engine or the electric motor (not shown) is transmitted to the driving shaft 10, the rotor 20 is rotated by the rotationally driven driving shaft 10. As the rotor 20 is rotated, the vanes 30 reciprocate with respect to the rotor 20, and the pump chambers 41 are repeatedly expanded and contracted.

The working oil in the tank 2 is sucked into the pump chambers 41 passing through the expansion regions 42 a and 42 c through the low pressure chamber 61 and the side ports 74 and 81 or through the low pressure chamber 61, the fluid chamber 54, and the side ports 74. At this time, as shown by arrows in FIG. 5, the working oil that has been sucked through the side ports 74 and 81 are guided towards the center side in the axial direction of the pump chambers 41 by the concave portions 23 and 24 formed in the outer circumferential surface 20 a of the rotor 20. More specifically, as an arrow A shown in FIG. 5, even when the working oil is sucked from the direction substantially perpendicular to the outer circumferential surface 20 a of the rotor 20, the flow of the working oil is directed smoothly so as to flow towards the center side in the axial direction of the pump chambers 41 by the side surfaces 23A and 24A that are formed to be inclined. Furthermore, the working oil is guided by the bottom surfaces 23C and 24C and the side surfaces 23B and 24B of the concave portions 23 and 24 towards the center side in the axial direction of the pump chambers 41. As described above, with the vane pump 100, by providing the concave portions 23 and 24 in the outer circumferential surface 20 a of the rotor 20, it is possible to smoothly guide the sucked working oil towards the center side in the pump chambers 41 in the axial direction. With such a configuration, because the pressure loss upon suction of the working oil is reduced, the suction efficiency of the vane pump 100 is improved.

As the rotor 20 is rotated, the pump chambers 41 into which the working oil has been sucked as described above pass through the contraction regions 42 b and 42 d. At this time, the working oil in the pump chambers 41 is discharged from the discharge ports 72.

With the vane pump 100, because the concave portions 23 and 24 are formed in the outer circumferential surface 20 a of the rotor 20, the dead volumes in the pump chambers 41 are increased. However, by providing the ridge portion 25 that projects from the outer circumferential surface 20 a of the rotor 20 in the radial direction, the increase in the dead volumes of the pump chambers 41 is suppressed. In this description, the dead volume means the volume of the pump chamber 41 moving from the contraction region 42 b or 42 d to the expansion region 42 a or 42 c (the volume of the pump chamber 41 in a state in which the pump chamber 41 is closed while moving from the discharge port 72 to the side port 74 or 81). The dead volume will be explained below in detail.

When the concave portions 23 and 24 are formed in the outer circumferential surface 20 a of the rotor 20, the dead volume in the vane pump 100 is increased correspondingly. High-pressure working oil that has entered when the dead volume was in communication with the discharge port 72 is trapped in the dead volume. Therefore, when the communication is established between the pump chamber 41 and the side port 74 or 81 as the pump chamber 41 moves from the discharge port 72 to the side port 74 or 81, the high-pressure working oil in the pump chambers 41 flows into the side port 74 or 81 where the pressure is low. At this time, the larger the dead volume is, the greater the amount of the working oil flowing into the side port 74 or 81 becomes. When the working oil flows into the side port 74 or 81 from the pump chambers 41 as described above, the suction of the working oil into the pump chambers 41 is disturbed, causing deterioration in the suction efficiency of the pump. Therefore, in the vane pump 100, by providing the ridge portion 25, the increase in the dead volume by the concave portions 23 and 24 is cancelled out. In other words, by providing the ridge portion 25 in the outer circumferential surface 20 a of the rotor 20, it is possible to reduce the dead volumes of the pump chambers 41 that has been increased by the concave portions 23 and 24.

If there is no enough space for providing the ridge portion 25 between the outer circumferential surface 20 a of the rotor 20 and the inner circumferential surface 40 a of the cam ring 40, the ridge portion 25 may not be provided. In addition, in the embodiment shown in FIG. 5, the ridge portion 25 is formed so as to be continuous with the side surfaces 23B and 24B of the concave portions 23 and 24. However, as in a modification shown in FIG. 10, the ridge portion 25 may be formed so as to be separated from the concave portions 23 and 24.

In addition, in the embodiment shown in FIG. 5, the bottom surfaces 23C and 24C are formed in the concave curved surface. However, as in the modification shown in FIG. 10, the bottom surfaces 23C and 24C may be formed to have flat surfaces. Furthermore, although the illustration in the drawings is omitted, flat surfaces and curved surfaces may be combined.

The embodiment described above affords the following effects.

The vane pump 100 includes the annular concave portions 23 and 24 formed in the outer circumferential surface 20 a of the rotor 20, and the concave portions 23 and 24 are inclined such that both side surfaces 23A, 23B, 24A, and 24B approach each other towards the bottom surfaces 23C and 24C. Therefore, the working oil that has been sucked from the side ports 74 and 81 is guided smoothly to the center side in the pump chambers 41 in the axial direction by the concave portions 23 and 24. With such a configuration, the suction efficiency of the pump is increased.

In addition, the side surfaces 23A and 24A of the two concave portions 23 and 24 are respectively formed at positions facing the cut-out portions 43 and 44. In addition, the side surfaces 23A and 24A of the concave portions 23 and 24 are formed to be inclined such that the flow of the working oil sucked from the cut-out portions 43 and 44 can be controlled. With such a configuration, although the working oil that has been sucked from the cut-out portions 43 and 44 flows into the pump chambers 41 from the direction substantially perpendicular to the outer circumferential surface 20 a of the rotor 20, the working oil is guided smoothly into the pump chambers 41 by the inclined side surfaces 23A and 24A of the concave portions 23 and 24 (towards the center side in the axial direction of the pump chambers 41). Therefore, the pressure loss upon suction of the working oil from the cut-out portions 43 and 44 is reduced, and so, it is possible to improve the suction efficiency of the vane pump 100.

Furthermore, with the vane pump 100, because the bottom surfaces of the concave portions 23 and 24 are formed of the concave curved surfaces, it is possible to further smoothly guide the working oil that has been sucked from the side ports 74 and 81 into the pump chambers 41. With such a configuration, the suction efficiency of the vane pump 100 is further improved.

In addition, by providing the ridge portion 25, with the vane pump 100, it is possible to reduce the dead volumes of the pump chambers 41 that has been increased by providing the concave portions 23 and 24.

The configurations, operations, and effects of the embodiment of the present invention configured as described above will be collectively described.

The vane pump 100 includes: the rotor 20 configured to be driven rotationally; the plurality of vanes 30 provided on the rotor 20 so as to be reciprocate in the radial direction of the rotor 20; the cam ring 40 having the inner circumference cam face 40 a with which the tip-end portions 31 of the plurality of vanes 30 are brought into sliding contact as the rotor 20 rotates; the first side member (the first side plate 70) and the second side member (the second side plate 80) arranged so as to sandwich the rotor 20 and the cam ring 40; the pump chambers 41 partitioned by the rotor 20, the cam ring 40, the adjacent vanes 30, the first side member (the first side plate 70), and the second side member (the second side plate 80); suction ports (the side ports 74 and 81) configured to guide the working fluid to the pump chambers 41; and the annular concave portions 23 and 24 formed in the outer circumferential surface 20 a of the rotor 20, wherein both side surfaces (both of the side surfaces 23A and 23B and both of the side surfaces 24A and 24B) of the concave portions 23 and 24 are respectively inclined so as to approach each other towards the bottom surfaces 23C and 24C.

In this configuration, even when the working oil that has been sucked from the suction ports (the side ports 74 and 81) flows into the pump chambers 41 from the direction substantially perpendicular to the outer circumferential surface 20 a of the rotor 20, because both side surfaces (both of the side surfaces 23A and 23B and both of the side surfaces 24A and 24B) of the concave portions 23 and 24 formed in the outer circumferential surface 20 a of the rotor 20 are respectively inclined so as to approach each other towards the bottom surfaces 23C and 24C, the sucked working oil is guided smoothly towards the center side in the axial direction of the pump chambers 41 by both side surfaces (both of the side surfaces 23A and 23B and both of the side surfaces 24A and 24B) of the concave portions 23 and 24. Therefore, the suction efficiency of the vane pump 100 is improved.

According to the vane pump 100, the suction ports (the side ports 74 and 81) are the cut-out portions 43 and 44 formed in at least one of the end surface 40 b of the cam ring 40 in contact with the first side member (the first side plate 70) and the end surface 40 c of the cam ring 40 in contact with the second side member (the second side plate 80), the cut-out portions 43 and 44 being configured such that the inner circumferential surface of the cam ring 40 and the outer circumferential surface of the cam ring 40 are communicated, and the side surfaces 23A and 24A of the concave portions 23 and 24 on the sides of the end surfaces 20 b and 20 c of the rotor 20 are respectively formed at positions facing the cut-out portions 43 and 44.

In this configuration, the working oil that has been sucked from the cut-out portions 43 and 44 is guided smoothly into the pump chambers 41 by the side surfaces 23A and 24A of the concave portions 23 and 24 on the sides of the end surfaces 20 b and 20 c of the rotor 20. With such a configuration, the suction efficiency of the vane pump 100 is improved.

According to the vane pump 100, the bottom surfaces 23C and 24C of the concave portions 23 and 24 are respectively formed of the concave curved surfaces.

In this configuration, because the bottom surfaces 23C and 24C of the concave portions 23 and 24 are respectively formed of the concave curved surfaces, it is possible to further smoothly guide the working oil into the pump chambers 41. With such a configuration, it is possible to further improve the suction efficiency of the vane pump 100.

According to the vane pump 100, the rotor 20 includes the two concave portions 23 and 24 and the annular ridge portion 25 formed between the two concave portions 23 and 24, the annular ridge portion 25 being configured to project in the radial direction from the outer circumferential surface 20 a of the rotor 20.

In this configuration, because the outer circumferential surface 20 a of the rotor 20 is provided with the ridge portion 25, it is possible to reduce the dead volumes of the pump chambers 41.

Embodiments of this invention were described above, but the above embodiments are merely examples of applications of this invention, and the technical scope of this invention is not limited to the specific constitutions of the above embodiments.

In the above-mentioned embodiment, although the vane pump 100 is provided with two concave portions 23 and 24, the vane pump 100 may have a configuration in which either one of the concave portions is provided depending on the flow of the working oil being sucked into the pump chambers 41.

This application claims priority based on Japanese Patent Application No. 2016-25853 filed with the Japan Patent Office on Feb. 15, 2016, the entire contents of which are incorporated into this specification. 

1. A vane pump comprising: a rotor configured to be driven rotationally; a plurality of vanes provided on the rotor so as to be able to reciprocate in a radial direction of the rotor; a cam ring having an inner circumference cam face with which tip-end portions of the plurality of vanes are brought into sliding contact as the rotor rotates; a first side member and a second side member arranged so as to sandwich the rotor and the cam ring; a pump chamber partitioned by the rotor, the cam ring, the adjacent vanes, the first side member, and the second side member; a suction port configured to guide working fluid to the pump chamber; and an annular concave portion formed in an outer circumferential surface of the rotor, wherein both side surfaces of the concave portion are inclined so as to approach each other towards a bottom surface.
 2. The vane pump according to claim 1, wherein the suction port is a cut-out portion formed in at least one of an end surface of the cam ring in contact with the first side member and an end surface of the cam ring in contact with the second side member, the cut-out portion being configured such that an inner circumferential surface of the cam ring and an outer circumferential surface of the cam ring are communicated, and a side surface of the concave portion on a side of an end surface of the rotor is formed at a position facing the cut-out portion.
 3. The vane pump according to claim 1, wherein the bottom surface of the concave portion is formed of a concave curved surface.
 4. The vane pump according to claim 1, wherein the rotor includes two concave portions and an annular ridge portion formed between the two concave portions, the annular ridge portion being configured to project in the radial direction from the outer circumferential surface of the rotor. 